Barrel extension assembly for stud drivers



Oct. 26, 1954 R. T. cATLlN BARREL EXTENSION ASSEMBLY FOR STUD DRIVERSFiled Jan. 8, 1954 INVENTOR. ROBERT I CAM/M Vonly light or medium power.

Patented Oct. 26, V1954 BARREL EXTENSION ASSEMBLY FOR STUD DRIVERSRobert T. Catlin, Stratford, Conn., assignor to Remington Arms Company,Inc., Bridgeport,v Conn., a corporation of Delaware Application January8, 1954, Serial No. 402,901

4 Claims. 1

This invention relates to an accessory for an explosively operated studdriver and more particularly to an accessory which effectively in.-creases the length of the barrel and thereby facilitates the use ofslower burning powders de,- sirable for propelling longer and heavierstuds.

There are available heavy duty tools which drive long and heavy studs bythe use of large centerre cartridges in barrels of length and diameterappropriate to such cartridges but such tools are quite expensive andare of limited use for general-purpose work, most of which requires Somecompetitive general-purpose tools are provided with interchangeablebarrels of varying length and diameter and with chamber insertsreceiving special cartridges, but such tools generally require separatehandling of stud, cartridge and chamber insert and are otherwise unhandyto use.

With a stud driver of the type shown in Patent No. 2,645,772, issuedJuly 21, 1953, to Merle H. Walker, thev design features which providefor superior performance of the tool, in particular the integral barrel,ejector, and heel cap type ammunition, make it impractical tointerchange barrels for increasing capacity.

Ordinarily, extremely fast burning powders are use with these tools toobtain maximum efficiency and to insure that the pressure level is wellbelow peak pressure when the stud reaches the end of the barrel,y withthe result that muzzle blast and recoil due to the escape of gas are notexcessive. If an attempt is made to increase driving capacity byincreasing the weight of the charge of such powders, or by increasingstud weight',y with any given charge, the chamber pressures exceed safelimits, tending to burst cartridge heads and to cause other diiculties.Capacity can be increased without exceeding safe pressure by the use ofcharges oi powder burning at slower rates, but such charges will stillhave a relatively high pressure when the stud reaches the muzzle of astandard length barrel and muzzle blast and recoil due to the jet ofescaping gas will be unusually severe.

These effects can be shown graphically by plotting; curves of barrelpressure as the ordinate againsttravel of the stud through the barrel asthe abscissa and the area beneath the curve is proportional totheavailable energy or the capacity of the powder charge for doing workupon the stud. The ordinate of such a curve at a time corresponding tothe emergence of the stud from the barrel isinclicative of the recoiland muzzle blast to be expected. With the extremely fast burning powderssuch a curve is sharply peaked and falls off rapidly to a relatively lowpressure', giving minimum blast and recoil when the stud emerges. Thepressure operated by the slow burning powders rises relatively slowly toa broad peak and maintains a relatively high level until after a studemerges from a standard barrel, with the result that blast and recoildue to gas escape are excessive. It is apparent that to drive the longerheavier studs without exceeding safe pressures, it is desirable to usethe slow burning powders with relatively greater area beneath apressure/travel curve, but to reach this end, dangerous pressures,excessive recoil, or excessive muzzle blast cannot be tolerated.

It is the object of this invention to provide a means of driving heavierstuds with general.- pu-rpose tools without excessive pressure, recoil,or muzzle blast, and without sacrificing the functional advantages of ageneral-purpose tool such as that shown in the Walker patent.

I contemplate that these objectives can be accomplished by providing fora standard tool an accessory comprising an extension barrel, a mufiier,and a guard which can be used interchangeably with a standard guard suchas that shown in the Walker patent or with the improved guards as shownin the copending applications of Robert T. Catlin, Serial Number252,949', filed October 24 1951, and issued as U. S. Letters. Patent No.2,669,716, on February 23, 1954, or Robert T. Catlin and Paul Hickman,Serial Number 300,716, filed July 24, 1952.

With the extension barrel the system remains closed for a longer timeand the pressure at the time the stud emerges from the extension ismaterially lower than with a short barrel; This is in itself enough tomateriallyV reduceV theA muzzle blast and recoil, but I find that theeffect can be augmented by the venting of the barrel which bleeds offinto the mui-lier a substantial fraction of the gas. and still furtherreduces recoil and muzzle blast. With this system I can take fulladvantage of the large area beneath the pressure curve, characteristicof slow burning powders, and the great capacity of' such powder fordoing work, without exceeding safe pressures or producing excessiverecoil and muzzle blast. By surrounding the barrel vents with a muiiler,I minimize the sound of the discharge and safely coniine the jets offlame and possibly particles of unburned power emerging from theI vents.l

The exact nature of the invention as well as other objects andadvantages thereof will more fully appear from consideration of thefollowing specification referring to the attached drawing in which:

Fig. 1 is a partial longitudinal quarter sectional view showing a studdriver like that in the Walker patent to which my invention has beenapplied.

Fig. 2 is a similar view showing the position of the elements of my-device and of the stud driver when held against a work surface in aninclined position.

Fig. 3 is a view similar to Fig. 2, showing the parts in positionagainst a Work surface ready for driving a stud.

Referring to the drawing by characters of reference, it will be seenthat I have shown a stud driver comprising a barrel I threadably orotherwise secured at its breech end to a frame plate 2. A breech block 3is hinged to the frame plate 2 by means of a bolt 4 on which the breechblock and frame plate have relative rotation to permit the exposure ofthe breech end of the barrel. An action tube cover 8 is secured to theframe plate in any convenient way and provides a housing enclosing aportion of the barrel adjacent the frame plate. An action tube 33 isslidably mounted on the portion of the barrel enclosed by the cover 8and itself encloses an action tube extension spring 31 which acts at oneend on a shoulder on the barrel. A finger 32 is mounted on the actiontube 33 and is projectable through aligned holes in the frame plate 2and breech block 3 to operate a sear lock 3| which prevents the firingof the stud driver unless the action tube is retracted upon the barrelinto substantial contact with the frame plate 2. The structure describedthus far is that shown in Walker Patent No. 2,645,772, to whichreference may be made for details of operation. Such reference will befacilitated by the fact that the reference numerals appearing thus farare applied to the same elements as in the patent.

This invention is an accessory for such a stud driver and comprises anaction tube extension 36 which is slidable on the barrel I andthreadably attached to the action tube 33. The spring 31 acts upon theinner end of the extension 35 and urges it to extend from the housing 8to the extent permitted by engagement of the action tube 33 with thehousing 8, as shown in Fig. 1.

The extension barrel is secured to the action tube extension 36 and isprovided with a bore of substantially the same diameter as that in thebarrel I. When the action tube extension 36 and action tube 33 are fullyretracted with the inner end of the action tube 33 stopped against theframe plate 2, the opposed ends of the barrel I and extension barrel 5are in contact as at I6 in Fig. 3 and the action tube finger 32 willhave released the sear lock 3 I.

The exposed end of the extension barrel 5 is tted with a replaceable,hardened ring 6 which forms a renewable work contacting end on theextension barrel and is provided with a bore 1 through which the stud isprojected.

A guard or shield assembly designated generally as 9 is supported on thefree end of the extension barrel 5 with capacity for limitedlongitudinal movement thereon by means of a guard sleeve |Il telescopedover the extension barrel. The extent of movement is limited by severalradial pins driven into the extension barrel 5 and engaged in aninternal groove I2 in the sleeve Ill, as well as by engagement with thering 6. In the position shown in Fig. 1, the guard is extended to amaximum and projects or more beyond the 4 end of the disk retainer 6. InFig. 2 the guard is at its other extreme position, which is that whichwould be occupied with the extension barrel and guard pressed rmlyagainst a work surface but inclined thereto at about a angle. Fordetails of the construction and operation of the guard assembly, whichmakes it impossible to re the stud driver when tilted beyond a safeangle, reference may be made to the copending application of Robert T.Catlin or of Robert T.

l Catlin and Paul Hickman, both referred to previously herein.

As in the copending application of Catlin and Hickman, the guardassembly is urged to its posimui-ller or expansion chamber I4 is mountedto enclose the extension barrel 5 and action tube extension 36 with achamber of substantial volume and being slidable on the extensionsserves to apply the reaction of the guard spring I3 to the outer end ofthe action tube cover 8. Within the muiier, vents I5 penetrate theextension barrel and a row of vents I6 communicate with the inner endface of the extension barrel.

Although the operation of the guard relative to safety control isidentical to that in the copending applications of Catlin and of Catlinand Hickman, theneed for reference thereto will be minimized by a briefsummary of the operating characteristics. Starting with the Fig. 1position, it will be seen that the guard assembly and action tubeassembly are both fully extendedfand that the finger 32 is remote fromthe sear lock 3| which must be operated to permit firing of the studdriver. In this position the tool is safe and may not be inadvertentlyfired.

If, as in Fig. 2, the tool is applied to a work surface, at an angle ofother than a side of the guard will rst engage the Work and the guardwill be retracted on the extension barrel against the action of theguard spring I3. In an inclined position, the guard sleeve III engagesone end of the muier I4 which is in contact with the action tube cover 8and stops further retraction of the guard. In the limiting position ofinclination, the end of the extension barrel will project forwardly fromthe plane of the end face of the guard and the action tube and nger 32thereon will not be retracted suiiiciently to operate the sear lock 3|.Fig. 2 illustrates a condition where the stud driver is inclinedrelative to the work to an extent slightly greater than necessary toprevent firing.

As the tool is brought into a position normal to the work surface, asshown in Fig. 3, the extension barrel is retracted to a position flushwith the end face of the guard and the inner end of the extension barrelis brought into contact with the end of the stud driver barrel. In thisposition the guard sleeve I3 is in engagement with the muiiier I4, whichin turn engages the action tube cover 8 and the action tube finger 32operates upon the sear lock 3| to permit the tool to be fired. Thisnon-tilt feature is common to the copending application of Catlin andHickman referred to above and to the application of Catlin, SerialNumber 252,949, earlier referred to.

Upon firing of the stud driver, there is an inevitable recoil reactionAtending to lift the tool away from the face of the Work. With thisdesign, however, the barrel I of the tool, to which the principalreaction is applied, must recoil for a distance equal to the initialretraction of the action tube 33 before there can be any substantialrecoil force acting on the extension barrel 5. Further, the extensionbarrel must recoil for a distance equal to the retraction of the guardassembly 9 thereon before there can be any substantial recoil forceapplied to the guard assembly. The guard assembly 9 thus remains incontact with the work surface and effectively protects the tool operatorfrom spalling concrete, metal scale, or other possibly injuriousmaterial.

The provision of the vents in the extension barrel relieves the gaspressure causing muzzle blast and tending to cause the barrel of thetool to recoil. The latter effect is particularly important With regardto the vents communicating with the space between the opposed ends ofbarrel and extension barrel, as at I6 in Fig. 3, in which space gaspressure tending to cause recoil is operating on an area materiallygreater than the cross-sectional area of the bore of the barrel. At thesame time, it may be noted that powder gas pressure action on theextension barrel at I6 tends to hold the extension barrel in closercontact with the Work face, thus further minimizing the chance that toolrecoil or the expansion of gas trapped beneath the guard 9 will causethe guard to lift from the Work surface and expose the operator to anyescaping material.

Although I have quite specifically described and illustrated only onemodification of my in-1 vention, I consider that invention to extend tocover a reasonable range of equivalents and modifications as set forthin the claims appended hereto.

I claim:

1. For use with a powder-actuated stud driver having a barrel throughwhich studs are projected and an action tube for releasing a safetydevice, said action tube surrounding said barrel and longitudinallyslidable thereon between an extended position in which the stud drivermay not be fired and a retracted position in which said safety device isreleased, an accessory device comprising an action tube extensionsecured to said action tube and slidable therewith on said barrel, andan extension barrel coaxial with and extending from said action tubeextension, said extension barrel having a bore of substantially the samediameter as the stud driver barrel, the end face of said extensionbarrel being in abutment with the muzzle of said stud driver barrel whensaid action tube and action tube extension are in said retractedposition thereon, said extension barrel then serving as a coaxialcontinuation oi' said stud driver barrel.

2. An accessory device as described in claim 1, said extension barrelbeing provided with gas vents to relieve gas pressure in the borethereof.

3. An accessory device as described in claim 2, at least a portion ofsaid gas vents communicating with the end face of said extension barrelin position to relieve gas pressure at the interface between the muzzleof the stud driver barrel and the end of said extension barrel.

4. An accessory device as described in claim 3, including asubstantially closed muffler chamber mounted on and surrounding saidaction tube extension and said extension barrel, said muffler chamberbeing positioned to receive gases emitted from said pressure relievingvents.

No references cited.

